Texas Math and Science Coaches Association (TMSCA) Science Practice Exam

Old red blood cells are filtered from the bloodstream by the spleen. In the spleen’s red pulp, macrophages engulf and break down worn or damaged RBCs, recycling iron and hemoglobin components. The iron can be reused elsewhere, and the heme is processed into bilirubin for disposal. The liver helps process bilirubin, but the primary site for removing RBC remnants is the spleen. The kidneys filter plasma to remove waste, not whole red blood cells, and the heart only pumps blood.